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util: logging symbols should convert using String(symbol) #927

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domenic opened this issue Feb 23, 2015 · 3 comments
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util: logging symbols should convert using String(symbol) #927

domenic opened this issue Feb 23, 2015 · 3 comments
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util Issues and PRs related to the built-in util module.

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@domenic
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domenic commented Feb 23, 2015 

var symbol = Symbol("My symbol");

console.log(symbol); // fine, logs Symbol(My symbol)
console.log("foo", symbol); // throws

Output:

$ iojs test.js
Symbol(My symbol)
util.js:34
      str += ' ' + x;
                 ^
TypeError: Cannot convert a Symbol value to a string
    at Console.exports.format (util.js:34:18)
    at Console.log (console.js:36:34)
    at Object.<anonymous> (c:\Users\Domenic\Dropbox\GitHub\whatwg\streams\reference-implementation\test.js:4:9)
    at Module._compile (module.js:444:26)
    at Object.Module._extensions..js (module.js:462:10)
    at Module.load (module.js:339:32)
    at Function.Module._load (module.js:294:12)
    at Function.Module.runMain (module.js:485:10)
    at startup (node.js:111:16)
    at node.js:799:3

Note that the correct way to stringify a symbol is with the explicit conversion, String(symbol), instead of implicitly with the + sign.

I can get to this after work if nobody else does first.
@vkurchatkin
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Is it the correct behaviour though? I thought it was v8 bug

@vkurchatkin vkurchatkin added the util Issues and PRs related to the built-in util module. label Feb 23, 2015
@domenic
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domenic commented Feb 23, 2015

Yeah, this is correct per spec and several TC39 meetings. It is dangerous to allow symbols to be implicitly converted to strings (and in some cases you just flat out can't do it, e.g. obj[prop] usually does an implicit string conversion). However explicit conversion is fine.

@cjihrig cjihrig mentioned this issue Feb 23, 2015
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cjihrig added a commit that referenced this issue Feb 24, 2015
@cjihrig
util: handle symbols properly in format()
ed3b057 
Currently, if util.format() is called with a string as its first
argument, and a Symbol as one of the subsequent arguments, an
exception is thrown due to an attempted implicit string conversion.
This commit causes Symbols to be explicitly converted.

Fixes: #927
PR-URL: #931
Reviewed-By: Domenic Denicola <[email protected]>
@cjihrig
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cjihrig commented Feb 24, 2015

Closed by ed3b057

@cjihrig cjihrig closed this as completed Feb 24, 2015
petkaantonov pushed a commit to petkaantonov/io.js that referenced this issue Feb 25, 2015
@cjihrig @petkaantonov
util: handle symbols properly in format()
2450921 
Currently, if util.format() is called with a string as its first
argument, and a Symbol as one of the subsequent arguments, an
exception is thrown due to an attempted implicit string conversion.
This commit causes Symbols to be explicitly converted.

Fixes: nodejs#927
PR-URL: nodejs#931
Reviewed-By: Domenic Denicola <[email protected]>
@jasonkarns jasonkarns mentioned this issue Nov 17, 2017
Closed
jasonkarns added a commit to testdouble/testdouble.js that referenced this issue Nov 17, 2017
@jasonkarns
Symbols must be stringified explicitly
ec31f02 
Apparently (nodejs/node#927 (comment)),
Symbols cannot be implicitly coerced to string.

Template stringification leverages implicit coercion, so we must
stringify propKey before sending it to the template.

Options for explicitly stringifying:

- `String(propKey)`
- `String.prototype.toString(propKey)`

Differences:

```
> String(undefined)
'undefined'
> String.prototype.toString(undefined)
''
```

In this case, `propKey` represents the key for the stubbed function. If
the key is `undefined`, it would be implicitly coerced to `"undefined"`
as the property key. So `String()` is the explicit converstion we want.
@jasonkarns jasonkarns mentioned this issue Nov 17, 2017
Merged
jasonkarns added a commit to testdouble/testdouble.js that referenced this issue Nov 18, 2017
@jasonkarns
Symbols must be stringified explicitly
b6dd645 
Apparently (nodejs/node#927 (comment)),
Symbols cannot be implicitly coerced to string.

Template stringification leverages implicit coercion, so we must
stringify propKey before sending it to the template.

Options for explicitly stringifying:

- `String(propKey)`
- `String.prototype.toString(propKey)`

Differences:

```
> String(undefined)
'undefined'
> String.prototype.toString(undefined)
''
```

In this case, `propKey` represents the key for the stubbed function. If
the key is `undefined`, it would be implicitly coerced to `"undefined"`
as the property key. So `String()` is the explicit converstion we want.

Four instances of this issue, each where tdFunction is invoked with a
dynamic name.
jasonkarns added a commit to testdouble/testdouble.js that referenced this issue Nov 18, 2017
@jasonkarns
Symbols must be stringified explicitly
8b2b9c3 
Apparently (nodejs/node#927 (comment)),
Symbols cannot be implicitly coerced to string.

Template stringification leverages implicit coercion, so we must
stringify propKey before sending it to the template.

Options for explicitly stringifying:

- `String(propKey)`
- `String.prototype.toString(propKey)`

Differences:

```
> String(undefined)
'undefined'
> String.prototype.toString(undefined)
''
```

In this case, `propKey` represents the key for the stubbed function. If
the key is `undefined`, it would be implicitly coerced to `"undefined"`
as the property key. So `String()` is the explicit converstion we want.

Four instances of this issue, each where tdFunction is invoked with a
dynamic name.
jasonkarns added a commit to testdouble/testdouble.js that referenced this issue Jan 17, 2018
@jasonkarns
Symbols must be stringified explicitly
a36a89c 
Apparently (nodejs/node#927 (comment)),
Symbols cannot be implicitly coerced to string.

Template stringification leverages implicit coercion, so we must
stringify propKey before sending it to the template.

Options for explicitly stringifying:

- `String(propKey)`
- `String.prototype.toString(propKey)`

Differences:

```
> String(undefined)
'undefined'
> String.prototype.toString(undefined)
''
```

In this case, `propKey` represents the key for the stubbed function. If
the key is `undefined`, it would be implicitly coerced to `"undefined"`
as the property key. So `String()` is the explicit converstion we want.

Four instances of this issue, each where tdFunction is invoked with a
dynamic name.
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@domenic @cjihrig @vkurchatkin